This present invention relates to a preparation method for high density fuels by the addition rearrangement of the compound pentacyclo[7. 5. 1. O.sup.2,8 . O.sup.3,7 . O.sup.10,14 ]pentadecane(C.sub.15 H.sub.22), in particular, by using a super acid as a novel catalyst to produce a series of hydrocarbon mixtures.
U.S. Pat. No. 4,059,644 discloses a process for making high density fuels by oligomerization of a mixture of cyclopentadiene dimer and methylcyclopentadiene dimer and methylcyclopentadiene dimer to produce their trimers and cotrimers followed by hydrogenation of the oligomerization product to obtain high density fuels. The trimers and cotrimers only constitute 40% of these oligomers. The density, melting point and net heat of combustion of the fuel mixtures are 1.02 g/ml, -30.degree. C. and 154,000 BTU/gal, respectively.
U.S. Pat. No. 4,401,837 issued to Burdette et al. discloses a process for the preparation of a high density fuel consisting of exotetrahydrotricyclopentadiene (EXOTHTC)C.sub.15 H.sub.22. In this method, endo-dicyclopentadiene as the starting material was used to produce trimers in a closed high temperature system. Then the trimers were catalytically hydrogenated and isomerizated to obtain high density exotetrahydrotricyclopentadiene fuel having the following properties: density: 1.0376 g/ml; freezing point: &lt;-40.degree. C. and net heat of combustion: 155,522 BTU/gal.
High density fuel for airbreathing engines are especially useful in jet aircraft and missiles in order to provide greater efficiency to thus achieve greater range. High density fuel permits maximizing the range of these aircraft by providing higher energy per unit fuel volume.
To perform satisfactorily in such applications, the fuel must meet certain physical property requirements. This generally means that the fuel must have a melting point no greater than, if not substantially below -20.degree. C. To provide high energy per unit volume, multiple ring compounds with a density approaching or exceeding 1.0 gm/ml must be employed.